Through making references to the biological explanations of altruism, especially the theories of kin selection and reciprocal altruism, the ethical thoughts of St. Thomas Aquinas, Wang Yang-ming, and some contemporary Christian and/or Confucian ethicists, this article attempts to engage Christianity, Confucianism and evolutionary biology in a fruitful tri-lateral dialogue on altruism. It argues that in addition to the dialogue between Confucianism and evolutionary biology as well as the dialogue between Christian theology and biology, the evolutionary perspective on altruism, especially the relationship between in-group altruism and out-group egoism, can also contribute fruitfully to the dialogue between Christianity and Confucianism